1. Field of the Invention
This application relates to cables. More particularly, this application relates to network cable construction.
2. Description of Related Art
Communications cables are broadly grouped into two arrangements, fiber optic cables and metal conductor cables, each of which has their own unique set of construction parameters that affect the quality of the communication signals carried therethrough.
Regarding metal conductor cables, one typical arrangement is the LAN (Local Area Network) cable that is usually constructed of four pairs of twisted insulated copper conductors encased within a jacket. Other larger cables may employ more pairs of conductors.
In this typical four pair LAN cable construction, in addition to the outer jacket, each of the eight primary conductors are individually coated with an insulation layer. Among the other components, LAN cables often include a cross-filler for better NEXT (Near End Cross Talk) performance. An exemplary LAN cable with a cross filler is shown in prior art FIG. 1. In each case, aside from electrical performance considerations, there are certain mechanical performance tests that need to be met. One such crucial test is the NFPA 262 flame test, which is a standard method of testing for flame travel and smoke generation for testing wires and cables that may be installed in air-handling spaces such as building ductwork.
In this context, FEP (Fluorinated Ethylene Polymer) resin, thanks to its outstanding electrical and flame performance, is a typical material choice for the LAN cable application. Aside from its use as the insulation on the primary conductors of the twisted pairs, FEP is also the currently the ideal choice for the material of the cross fillers as it has excellent electrical properties and good flame and smoke performance. Alternative prior art arrangements have used mixtures of LDPE and VLDPE (Low Density and Very Low Density Polyethylene) with flame retardant fillers